Combined continuous sintering and cooler machine



June 6, 1961 P. J. HOMAN 2,987,307

COMBINED CONTINUOUS SINTERING AND COOLER, MACHINE Filed June 18, 1958 6Sheets-Sheet l INVENTOR. .Rqul. J #0009 mM M m.

June 6, 1961 HQMAN 2,987,307

COMBINED CONTINUOUS SINTERING AND COOLER MACHINE Filed June 18, 1958 6Sheets-Sheet 2 INVENTOR. 304. u/. #007 A 7-7-0 radar MACHINE P. J. HOMANJune 6, 1961 COMBINED CONTINUOUS SINTERING AND COOLER 6 Sheets-Sheet 3Filed June 18, 1958 SPI A INVENTORIL/ Paul. J. HomA June 6, 1961 P. J.HOMAN 2,987,307

COMBINED CONTINUOUS SINTERING AND COOLER MACHINE Filed June 18, 1958 6SheetsSheet 4 INVENTOR. f4 (.14 J 79809.4

June 6, 1961 P. J. HOMAN 2,987,307

COMBINED CONTINUOUS SINTERING AND COOLER. MACHINE Filed June 18, 1958 6Sheets-Sheet 5 III 65 l I l I INVENTOR. 5 pfiUL J hamnrl.

June 6, 1961 P. J. HOMAN 2,987,307

COMBINED CONTINUOUS SINTERING AND COOLER MACHINE Filed June 18, 1958 6Sheets-Sheet 6 INVENTOR. Pa u/ J. HOMA United States Patent 2,987,307COMBINED CONTINUOUS SINTERING AND COOLER MACHINE Paul J. Human,Pittsburgh, Pa., assignor to Koppers Company, Inc., a corporation ofDelaware Filed June 18, '1958, Ser. No. 742,809 7 Claims. (Cl. 266-21)The present invention relates to improvements in an apparatus forcombined continuous sintering and cooling of material, and moreparticularly, to continuous sintering machines of the modern typeconstituted of an endless train of pallets movable in side by sideabutting relation successively along upper and lower strands, andprovided with crushing and screening means for delivery of crushed andscreened hot sinter from the sintering pallets to sinter cooler pallets.

The primary object of the present invention is the provision of amachine of the aforesaid modern type having as a novel and importantcharacteristic a mode of construction and operation which very greatlysimplifies, and reduces the cost of, such sintering plants and theirgeneral operation.

Modern sintering plants incorporate separate machines in tandem forcontinuous sintering and cooling of the sinter with a crusher and screenintermediate the discharge end of the sintering strand and the feed endof the cooling strand for more effective and high capacity operation insintering and cooling. Both machines'usually require an endless loop ofmoving pallets. The sintering operation utilizes the top strand only ofthe sintering 7 sintering machine, through the crusher, over the screen,

and then on to the cooler. These machines are usually built in tandem,with the result that a very long and high plant is necessary.

In accordance with the present invention, there is provided for thepurpose of capacity a continuous sintering crushing and coolingcombination machine which utilizes the top strand for the sinteringoperation, the intermediate area, and the bottom or return strand forthe cooling operation.

Hot sinter is discharged from the top strand directly into a crusher andscreen located in the area between the upper and lower strands fordelivery to the bottom strand. The screen sizes the sinter, placing thesize on the bottom strand and the fines being withdrawn from the machineand recycled to mix with new material to be sintered on the top strand.

Air is pulled down through the top sintering strand by one set of fanswhile air is blown up through the lower cooling strand by another set offans.

The drive of the upper sintering strand is at the feed end and issynchronized with a drive at the opposite end of the strands for movingthe pallets on the lower strand, so that the machine is fully andmechanically synchronized.

The pallets run on a continuous track for both strands but the palletsdo not turn upside down to enter the lower strand as they do now on thepresent day modern machine. Instead, they return on the lower returntrack or strand in an upright position, so that the grate bars bothcooling and sintering.

Patented June 6, 1961 For this, means are provided at the hot sinterdischarge end of the strands for tilting the pallets, as they leave theupper strand, toward the area between the upper and lower strands, todischarge the hot sinter for crushing, and for restoring the pallets toupright position as they enter the lower strand, and means are providedat the cool sinter discharge end of the strands for tilting the pallets,as they leave the lower strand, toward the area outside the strands, todischarge the cooled sinter from the machine, and for restoring thepallets to upright position as they enter the upper strand.

A particular advantage of the present machine is that a substantialsaving in cost of construction and operation is realized, as most of thepresent day tandem type of cooler equipment is eliminated, and greatsavings are accomplished in the plant itself, due to a reduction inlength and height of plant area, reduction of material handlingequipment, and simplification of operation.

The machine as shown having 130 pallets, with working and 30 empty, hasthe same capacity of present day modern machinery which requires 260pallets for the sintering and cooling operation, with 104 working and156 empty. The saving of pallets in a sintering and cooling plant notonly represents a substantial amount in initial investment, but alsorepresents a substantial amount in reduced maintenance cost. In additionto the above, a substantial savings is realized due to the eliminationof the dual equipment, such as the machine frame, drive, foundations,controls, electrical equipment, material handling equipment, mechanicalequipment, etc., required by the present type of tandem sinter machineand cooler.

In addition to the general objects recited above, the invention has forfurther objects such other improvements and advantages in constructionand operation as may be found to obtain in the apparatus and mode ofoperation hereinafter described or claimed.

In the accompanying drawings, forming a part of this specification, andshowing, forthe purpose of exemplification, the best mode contemplatedby the inventor for carrying out the invention, but without limiting theclaimed invention specifically to such illustrative instance orinstances:

FIG. 1 is a schematic side elevational view of a combined continuoussinter and cooler machine embodying the present invention.

FIG. 2 is a vertical side elevational view of the lefthand side end ofthe machine of FIG. 1 showing on an enlarged scale the drive and feed ofthe'upper strand and the discharge operation for the cooled sinter fromthe lower strand.

FIG. 3'is a like view illustrating the right-hand side of the machine ofFIG. 1 and showing on an enlarged scale the discharge of the upperstrand to the crusher and screen, and the drive of, and feed back of thecrushed hot sinter into, the pallets in their restored upright positionon the lower strand.

FIG. 4 is a vertical cross sectional view taken on the line 4-4 of FIG.3, to show the trackways and wheels for the pallets, the pusher racks atthe tops of the ends of the pallets, and the outlet wind boxes for theburner gases from the upper sinter strand and the air inlet wind boxesfor the lower cooler strand.

FIG. 5 is a vertical cross sectional view taken on the, line 5-5 of FIG.3, to show the relationship of the crusher and screens to the tiltingmeans between the two strands and the driving mechanism and hold backpinion for the lower strand.

FIG. 6 is an enlarged vertical cross sectional view showing the collarsand pinion and rack mechanism for FIG. 7 is a perspective view moreclearly showing aesasor transfer of the pallets from the upper graterail 30 to grooves 37 in sprockets 13.

In its present embodiment, the invention is incorporated in-an oresintering machine with conventional elements including a crusher andscreen between the strands, andin the preferred embodiment of theinvention the machine also includes in its construction novel mechanismfor tilting and restoring the pallets to upright position during theirtransfer at the opposite ends of the machine h'om one strand to theother, and twin pairs of tracks for each strand, with idler collars onthe pallets and a pair of sprockets at each end of the machine forcoaction with the idler collars to control the progress of movement ofthe pallets from each strand to the other for progressive discharge ofclinker to the lower strand for cooling after crushing and progressivetransition of the pallets between the strands. For convenience, thepresent invention will be confined to this use of the invention. Theinvention is not limited in all its aspects to this preferred embodimentof the invention, since much of the advantage of the invention isattained with the use of different means for tilting and restoring thepallets at each end of the machine, and with discharge of the cooledclinker to the interior rather than the exterior of the upper and'lowerstrands for takeoff of the finished product, Hence, the invention is notlimited in all its aspects to the specific means disclosed as the bestmode of operation hereinafter described and claimed.

As shown on the drawings, the machine incorporates in its constructionthe following conventional elements commonly employed in the modern artfor combined continuous sintering and cooling, namely: a continuoussinter machine of the endless conveyor type comprising an upper strandwith pallets 11, and a lower strand or run 12 with pallets 11, sprockets13, at each end of the machine, wind boxes 14 below the strands foroff-flow of burnt gases from the pallets undergoing sintering in theupper strand to a stack 15 through a gas flue line 16 and exhausters 80,and wind boxes 17 for inflow of cooling air from blowers 90 to thebottoms of the pallets undergoing cooling of the sinter or clinker inthe lower strand, as well as a crusher 18 and screen 19 for crushing andscreening the hot sinter or clinker from the upper strand before coolingthe same in the lower strand.

The wind boxes are sealed by wear bars 21 and seal bars 22, FIGURES 4and 6, in the conventional manner, and the upper sinter strand isprovided with a hearth layer feed hopper 23, a sinter material feeder 24in the form of a sinter mix roll feeder for supply of material to besintered, as well as an ignition furnace 25.

The elements of the structure thus far described is typical of theelements of this type of sintering plant and hence, need not bedescribed 'in further detail.

In previous practice, for full capacity and most'efiicient operation,two machines in tandem with a crusher and screen in between, has beenadopted as standard to make full use of the upper strand of the firstmachine for sintering, and the upper strand of the second machine forcooling. 7

In accordance with the present invention, this principle of operationfor full capacity and efiiciency'is carried out in'a single machine bycontinuing the full use of the upper strand of the machine for sinteringand by crushing the sinter cake in the intermediate area and therebymaking '7 full use of the pallets in the lower strand for cooling thecrushed hot sinter'from theupper strand.

Accordingly, the usual form of crusher and screen as used heretofore intandem is located'instead in the intermediate area 26 between the upperstrand and the lower strand, at'the ends thereof at which the palletsleave the upper strand with hot sinter, This entails tilting thepalletslor' their gratestowardtheintermediate area 26 7 ffor dischargeof the hot sinter from the pallets, as they leave; the upper strand,into the crusher and screen -in the 1 intermediate area 26 for crushingand screening the material before it is fed back into the pallets in thelower strand, and entails restoring the pallets, or their grates, toupright or horizontal position to receive the crushed sinter from theupper strand for cooling of the sinter as the pallets move into andalong the lower strand. It also entails tilting the pallets, or theirgrates, either into the intermediate area 26 or to the area outside thestrands at the opposite end of the machine for discharge of the cooledsinter as the pallets leave the lower strand to enter the upper strandand entails restoring the pallets or their grates to upright orhorizontal position for sintering as they move again into and along theupper strand.

For tilting and restoring the pallets, or their grate bars, each palletis provided with a pair of front and rear wheels 27, 28, on each end 29,FIGURE 4, and each strand is provided with twin pairs 30, 31 of railsover which the front 27 and rear 28 wheels ride to supportthe palletsfor sliding movement over the Wind boxes of the upper and lower strands.The front wheels 27' at each end of the pallets are located at a higherlevel than the rear wheels 28, and ride on one pair of tracks 30, overeach "strand. The rear wheels 28 at each end of each pallet ride overthe other pair of tracks 31 which are located at a lower level over eachstrand. The upper pair of tracks 34} are endless, being looped at 'eachend of the strands at the opposite ends of the machine. The lower pairof tracks 31 are interrupted at each end of the machine so that thepallets, or their grates 20, can tilt by gravity at each end of themachine, to discharge the hot sinter to the crusher 18 in the interiorarea 26 as the palletsleave the upper strand 10 with the hot sinteror'clinker, and to discharge the cooled sinter from the pallets 11either to the exterior of the strands, or to the interior 26, at'thecool end of the machine as the pallets leave the lower strand 12.

The lower pairs of tracks 31 in the lower strand 12 are inclined 32upwardly, FIGURE 3, around the hot end of the machine to a horizontallevel below the axes 33 of rotation of the sprockets 13, but above thelower periphery of the sprockets 13, to be in a position to support therear wheels 28 of the pallets as they leave the sprocket 13 and therebybegin to restore the pallets to upright horizontal position as theyenterthe lower strand 12. At the cool end of the machine, FIGURE 2, the lowertracks 31 of the upper strand 10 are constituted a curved portion 34,downwardly around the axis 35 of retation of each'sprocket 13,, to.engage the lower rear wheels 28 as they rideabove the axis 35 ofsprocket 13 to restore the pallets 11 to horizontal for the upper strand10. At each of the hot 33 and cool 35 ends of the ma the upper strand 10extend downwardly around said axis 33, 35 of rotation to overlap theupper tracks 39 in the lowerstrand 12, to form a confined guideway 36for the fr'ontwh'eels 27 of the pallets 11 during the rotation of thepallets from one strand to the other by'the sprockets To control theprogressive movement of the pallets from each strand to the other, apair of sprockets 13 are provided at each end '33, 35 of 'the machinetorotate on said axes 33 of rotation; The sprockets 13'are providedfreely rotatable collar 39 to seat'in the grooves 37 of the sprockets13. The sprockets 13 thus support the pallets 11 while allowing them totilt and restore to upright position during their transition from onestrand to the other. I a a U J P ll t sms e s qne h stra d 'lflilz, i wcessive abutting relation. For this,thepa lle ts- 1 1 are pro} vided,FIGURES 2, 4, 6, with a rack 41 along the tops of the ends 42 of thepallets 11 which are driven by separate pusher pinions 43 at theentrance ends of the upper and lower strands. To engage the pallet racks41 with such pusher pinions 43 as the pallets leave the sprockets 13,retractable pushers 44 are provided, FIG- URES 2, 3, 5, at each end ofthe machine to engage the rear sides of the ends 42 of the pallets asthey leave the sprockets 13 and push the entering pallets forward intoabutting relation with the preceding pallet until the pusher pinion 43engages the rack 41 of the entering pallet. These retractable pushers 44are reciprocated by slides 45 which ride on wheels 46. The slides 45 areeach operable by a crank 47 driven by a drive shaft 48 which also drivesthe pusher pinions 43 to push the pallets along the upper and lowerstrands to engage their racks 41 with the pinions 43. The sprockets 13are like wise driven, through a sprocket 49, chain 51, and pinions 52,by drive shafts 48, 53, that drive the pusher pinions 43 and cranks 47.The drive shafts 48, 53 for the upper and lower strands are driven inunison through the sprockets 55 and chain 56 connection with main driveshafts 57 operable through reduction gearing 58 by means of electricmotors 59 which are synchronized to move the pallets '11 on the sinterstrand in synchronism with the pallets 11 on the cooling strand 12.

Since the pallets slide down by gravity, from the sprockets 13 at thehot discharge end of the upper sinter strand to the entrance end of thecooling strand 12, they might tend to jar the pallets that are alreadyahead on the cooling strand 12 if left to fall freely by gravity withoutrestraint. To eliminate this, the drive shaft 53 for the sprockets 13for the hot end 33 of the machine is provided with a hold back pinion 61which meshes with the racks 41 of the pallets 11 just ahead of the crankdriven pusher 44 and pusher pinion 43 to hold back the descent of thepallets 11.

As shown in FIGURE 5, this drive shaft 53 is connected by sprockets 55and chains 56 with the motor 59, and carries a pinion 54 in mesh withthe pinion 52 to drive the chain and sprocket drive for the sprocket 13at the cool end of the machine and is also connected by a sprocket wheel62 and chain 63 and sprocket 55 with a shaft 48 for driving the crankpusher 44 and pusher pinion 43 for the cooling strand.

The crusher is rotated by a separate motor drive 65, FIGURE 5, and thescreens are of the conventional shaker screen type which are driventhrough an eccentric 66 by means of a further separate motor drive 67.

The ore in adjacent pallets 11 sinters together as a single mass, andthe pallet charges are cracked apart as they leave the upper strand 10to ride on the sprockets 13, to tilt to discharge the sinter forcrushing of the sinter in the intermediate area 26 before the sinter isrefilled in the pallets in the lower strand for cooling, a hump 68 isprovided in the rails of the lower track 31 at the discharge end of thesinter strand, to cause the rear side of the pallets 11 to rise as theypass over the hump 68 and thereby shear the cake in adjacent palletsapart.

To avoid wear and weight on the rim or perimeter of the sprockets 13 asa result of the pallet parts riding on the rim or perimeter of thesprockets 13, until the grooves 37 rotate into position to grasp thecollars 39 of the pallets, the ends of the rails of both the upper andlower tracks are inclined to carry such weight and thus avoid wear ofthe rims of the sprockets until the grooves 37 arrive in position toreceive the collars 39. The collars being freely rotatable on thepallets, the collars merely rotate freely countercurrently to thedirection of rotation of the sprockets 13, thus avoiding weight and wearon the sprockets 13.

In operation, the motors 59 are operated in synchronism to drive thesprockets 13, pusher pinions 43, and pusher rams 44 in unison so thatthe pusher pinions 43 6 for the strands 10 and 12 make one revolutionper pallet length, and the sprockets 13 rotate 45 as said pinions 43make one revolution. The pallets 11 move continuously along each strand10 and 12 and around each end 33, 35 of the machine in timed sequence.During this movement, a hearth layer is laid continuously by hopper 23and a mixture to be sintered laid on top of the hearth layer by the mixroll feeder 24, which is thereafter ignited by the furnace 25. Theburner gases flow down through the sinter mix on, and through, thepallet grates 20 to the wind boxes 14, from which the hot gas flowsthrough the flue line 16 to the stack 15. After the pallets ride thehump 68, the grooves 37 of the sprockets 13 at the hot and 33 of themachine pick up the collars 39 of the pallets 11. These collars 39 areon the same shaft 38 as the front wheels 27 of the pallets. As thesprockets 13 rotate they support the pallets 11 while the frontwheels 27ride through the guideway 36 formed by the looped overlapping uppertracks 30. The pallets being supported only on the shafts 38 of theirfront wheels 27 during their transition by the sprockets 13, the rearportion of the pallets descend by gravity, pivoting around the axis 38of the front wheels 27. This tilts the grate 20 toward the interior area26, and the hot sinter cake drops into the crusher 18. From the crusher18 the ground sinter cake is screened in 19 to separate the fines fromthe coarse, to aid the cooling in the lower strand 12. The

coarse particles are fed back into the pallets 11' in the lower strandby chutes and the fines are withdrawn from the area 26 by a conveyorwhich sends them back to be mixed with fresh ore to be fed to the sinterstrand by the mix roll feeder 24. During this time, the pallets 11 onthe sprockets 13 leave the sprockets as their rear wheels 28 ride on thetop of the inclined part 28, 32 of the lower strand tracks, whichelevates them to horizontal upright position. The descent of the palletsis controlled by the re-engagement of the pallet racks 41 with the holdback pinion 61. Pallets which have passed this pinion 61 slide on towardthe last preceding pallets on the cooling strand 12 which is beingpushed forward by the pusher pinion 43; The pusher ram 44 pushes eachnext pallet 11 to enter the cooling strand 12 up against the lastprevious one as it moves away from pusher pinion 43, so that the nextfollowing pallet is positively pulled into driven engagement with thepusher pinion 43.

As the pallets move up along the tracks 31 in the lower run 12 theyfirst receive the oversize of the crushed sinter from the screen 19,which sinter is thereafter cooled as the pallets 11 move up the tracksover thewind boxes 17. For this, air from blowers enters the wind boxes17 from air lines 60. Thence the air passes up through the gates 29 ofthe pallets on the lower strand 12 and through the ground sinter cake.The air leaves the top of the bed on the pallets and passes out into thesurrounding atmosphere through the intermediate area 26.

At the discharge end of the cooling strand, the upper wheels 27 on eachpallet enter the guideway 36 formed by the overlapping upper tracks 30of the upper and lower strands 1t) and 12, and the collars 39 are pickedup by the grooves 37 of the sprockets 13 which carry the pallets 11 upto within reach of the pusher ram 44 which pushes the pallets forwardinto side by side contact with the preceding pallet until the pinion 43engages the rack 41 on the pallet so pushed forward. During this time,the rear wheels leave the lower tracks 31, and the pallet tiltsdownward, pivoting around the axis 38 of the shaft which carries thecollars 39 and the forward wheels 27, thus discharging the finallycooled sinter product into the discharge hopper 71 for removal as theend product from the machine. As the pallets are carried up above theaxis 35 of the sprocket 13, the curved portion 34'of the lower rails 31urge the rear half of the pallets upward around the axes 38 of thecollars 39 to restore the grates of the pallets to upright horizontalposition'for engagement with the pusher ram 44. a

. The invention in itsbroader aspects is also useful with other meansthan theones shown for transferring, tilting andpushing the pallets, andwith other means for screening and crushing the'hot sinter cake. Forinstance, the invention in its broader aspects, as well as in its bestmode of operation, is also of utility without screening the crushedsinter cake before cooling, and is also of utility without passage ofthe fines from the chute of the screen 19 to the pallets in the coolingstrand 12 after the filling of the pallets with the oversize from thescreen 19.

The invention as hereinabove set forth is embodied in a particular formof construction but may be variously embodied .within the scope of thefollowing claims.

I claim:

1. Apparatus for continuous sintering and cooling, comprising: an upperstrand of wind box means; a lower strand of wind box means underneaththe upper strand of wind box means; pallets movable in side by sideabutting relation successively across the top of said upper strand;pallets movable in side by side abutting relation successively acrossthe top of said lower strand in the op posite direction to the movementof the pallets in the upper strand; means for layering sinter materialon the pallets in said upper strand; means for igniting the top of thematerial on the pallets in said upper strand; means for exhaust of hotgases from the wind box means of the upper strand; means fortransferring pallets containing sinter successively from the upperstrand to the entrance end of the lower strand including means fortilting the pallets toward the intermediate area between the upper andlower strands as they'leave the upper strand for discharge of hot sinterfrom the pallets in the intermediate area above the pellets in the lowerstrand, and means for restoring the discharged pallets to uprightposition as they enter the lower strand; a crusher disposed in theintermediate area between the upper and lower strands in position toreceive hot sinter from the pallets as they tilt and to discharge thecrushed sinter to the restored pallets in their upright position at theentrance end of the lower strand; means for introducing cooling air intothe wind box means of the lower strand to cool the crushed sinter in thepallets during their successive movement thereacross, and means fortransferring pallets containing cooled sinter successively from thelower strand to the upper strand in advance of the means for layeringsinter material thereon, including means for tilting the pallets as theyleave the lower strand for discharge of cooled crushed sinter from thepallets in the lower strand, and

means for restoring the discharged tilted pallets to upright position asthey enter the upper strand, and in which the transfer means comprisescurved loops of an endless upper trackway, the means for tiltingcomprises a rotatable bearing eccentrically disposed on each pallet forsupporting the pallets on the curved loops, whereby the pallets tilt bygravity when so supported on the loops of said endless trackway, and themeans for restoring the pallets to upright position comprises aninterrupted trackway for both strands that engages another member on thepallets which, in conjunction with said endless trackway, maintains thepallets upright in the upper and lower strands, and which trackway hasextensions at the en trance ends of the upper and lower strands toelevate the pallets around the axis of said eccentrically disposed.bearing'on' the pallets to restore the pallets to upright trolledmovement of the pallets during their transfer from each strand to theother.

3. Apparatus for continuous sintering and cooling, comprising: an upperstrand and a lower strand under- 7 neath the, upper strand, each strandcomprising two pairs of tracks with pallets movable inside, by sideabutting,

relatiomsuccessively along the tracks by means-eta of frontand rearwheels at each of the oppositeends of the pallets with the front wheelsriding on one pairof the tracks and the rear wheels riding on the otherpair of tracks and with one of the wheels of the set eccentric strand;sprockets with peripherally spaced supporting parts in position forrotatably engaging a part on the axis of the eccentric wheels of thesinter containing pallets for tilting the pallets toward theintermediate area between the upper and lower strands for discharge ofhot sinter from the pallets into the intermediate area above the palletsin the lower strand as they leave the upper strand and for control ofthe movement of the tilted pallets from the sinter strand toward thecooling strand underneath; cam tracks extending from the periphery ofthe lower part of said sprockets to the tracks in the lower strand forrestoring the tilted pallets to upright position as they slide bygravity from the sprockets to the lower strand;

a crusher disposed in the intermediate area between the.

upper and lower strands in position to receive hot sinter from thepallets leaving the upper strand as they tilt and to discharge thecrushed sinter to the restored pallets in their upright position at theentrance of the lower strand; means for introducing cooling air to thecrushed material in the pallets in the lower strand; sprockets withperiphorally spaced supporting parts in position for rotatably engaginga part on the axis of the eccentric wheels of the cooled sintercontaining pallets for tilting the cooled sinter pallets as they leavethe lower strand for discharge of cooled, crushed sinter toward an areabeyond the lower strand and for control of the movement of the tilted,cooled pallets from the cooling strand toward the sinter strand; and camtracks extending from said sprockets to the upper strand tracks forrestoring the cooled tilted pallets to their upright position in advanceof their entry to the upper strand before the means for layeringmaterial thereon.

4. Apparatus as claimed in claim 3 and which includes.

racks on the pallets for driving engagement with driving pinions forpushing the pallets along the strands, a driving pinion in each strandfor rotatable driving engagementwith the racks to push the same alongthe strands, and a sliding pusher in each strand for pushing each palletinto rack meshing relation with the driving pinions for the strands.

5. Apparatus as claimed inclaim 3 and which includes racks on thepallets for driving engagement with driving pinions for pushing thepallets along the strands, a driving pinion in each strand for rotatabledriving engagement with the racks to push the same along the strands, aslid ing pusher in each strand for pushing eachipallet into rack meshingrelation with the driving pinions for the strands, and a hold-backpinion for rotatably engaging the racks as they slide down the camtracks to enter the lower strand, 'for prevention of jar of the palletsin the.

lower cooling strand by the free gravity movement of the pallets towardthe cooling strand.

6. Apparatus as claimed in claim 3 and which includes racks on thepallets for driving engagement with driving pinions for pushing thepallets along the strands, a driving'pinion in each strand for rotatabledriving engagement with the racks to push the same along the strands, asliding pusher in each strand for pushing each pallet into rack meshingrelation with the driving pinions for the strands, a hold-back pinionfor rotatably engaging the racks as they slide down the'carn tracks toenter the 'lower strand, for prevention of jar of the pallets in thelower cooling strand by the free gravity movement of the pallets towardthe cooling strand,1 and a hump in one of the pair of tracks in theupper strand over which each pallet rides in advance of the sprocket atthe hot end of the sinter strand, for shearing the sinter cake in thepallets from the cake in the next following pallet on the upper strand.

7. Apparatus as claimed in claim 3 and which includes racks on thepallets for driving engagement with driving pinions for pushing thepallets along the strands, a driving pinion in each strand for rotatabledriving engagement with the racks to push the same along the strands, asliding pusher in each strand for pushing each pallet into rack meshingrelation with the driving pinions for the strands, a hold-back pinionfor rotatably engaging the racks as they slide down the cam tracks toenter the lower strand, for prevention of jar of the pallets in thelower cooling strand by the free gravity movement of the pallets towardthe cooling strand, a hump in one of the pair of tracks in the upperstrand over which each pallet rides in advance of the sprocket at thehot end of the sinter strand, for shearing the sinter cake in thepallets from the cake in the next following pallet on the upper strand,

and means for rotatably driving the sprockets, driving pinions, andsliding pushers in synchronism.

References Cited in the file of this patent UNITED STATES PATENTS

